The next special, Doctor Who: The Waters of Mars airs on BBC AMERICA, Saturday December 19, 9:00pm ET/PT. It stars Tennant and British stage and screen actress Lindsay Duncan (Rome, Langford) as Adelaide, his cleverest and most strong-minded companion. All will be revealed as the Doctor and his companion Adelaide face terror on the Red Planet in one of the scariest adventures yet. Peter O’Brien (Casualty, Neighbours) guest stars as Ed, Adelaide’s second-in-command at the base.

The Waters of Mars is written by Russell T Davies (Torchwood, Queer as Folk) and Phil Ford and directed by Graeme Harper. The executive producers are Russell T Davies and Julie Gardner (Torchwood, Life on Mars).

The remaining episodes, starring Tennant, will air over the holiday season as a two-part special. Airdates will be released in early December. Tennant shot a total of four specials before exiting the role - Planet of the Dead was the first one to air, last July, on BBC AMERICA.

Immediately after this morning's press screening, outgoing Time Lord David Tennant and outgoing exec producer Russell T Davies took questions from the gathered journos. A full transcript follows:

How does this special compare to the others?

David: "It tells a different sort of story, I think, and it's a long time into the episode before The Doctor takes control. That's what's unnerving about it - it's not the standard structure. We expect The Doctor to take control earlier - we expect The Doctor to know how he's going to do it and how he's going to win through and he doesn't. Even though he wins in the end it's a bitter sweet victory. People die. That's part of the story we have to tell to go where we're going."

Do you think 'Waters of Mars' can still be viewed by children? It's very dark in places.

David Tennant today admitted that filming his final scenes for Doctor Who had been "very emotional" – and revealed what his final lines in the lead role will be.

Tennant also admitted he was "jealous" of Matt Smith, who will be seen taking over his role as the Doctor next year.He was speaking at the London launch of The Waters of Mars, the first of three remaining Doctor Who specials to be broadcast on BBC1 before the end of the year. They are a swansong for Tennant, after four years in the lead role, and for Russell T Davies, the executive producer and showrunner responsible for Doctor Who's hugely successful reinvention.Smith takes over from Tennant for next year's fifth series of the revived Doctor Who, which is being overseen by new showrunner Steven Moffat, who has written award-winning episodes of the drama including Blink, The Empty Child and The Girl in the Fireplace.The Waters of Mars is to be broadcast on BBC1 on Sunday 15 November at 7pm, with the…

David Tennant said he had to keep a "stiff upper lip" while filming his final scenes for Doctor Who."It was very emotional saying cheerio," Tennant said after a screening of latest adventure The Waters of Mars, to be shown on BBC One on 15 November. "There's lots of scenes in the final episode that are very sad, and were very sad to play." He added: "On the actual final day I was a bit of a puddle, but kept a mildly stiff upper lip." The Scottish actor, who took on the role of the Time Lord in 2005, admitted he had been a "nervous" about seeing another actor on the role. "I'm thrilled that it's carrying on," he said, "and know that everyone who's there is a great choice, but of course you feel a bit proprietorial." Tennant is being replaced by actor Matt Smith, 27, who will appear as the 11th Doctor next year.The Waters of Mars will be followed by two episodes over the Christmas holiday that will see…

Doctor Who star David Tennant and writer Russell T Davies talk to Lizo Mzimba about The Waters of Mars, the first of David Tennant's final three adventures as the Time Lord which will be broadcast in November.

The ratings for Doctor Who spin-off The Sarah Jane Adventures broke past the million mark yesterday afternoon for the first part of David Tennant’s crossover appearance in the serial The Wedding of Sarah Jane Smith. The much anticipated crossover had been widely published and paid off in terms of ratings. According to early overnight figures over 1.3 million viewers tuned in to see the first part of the serial.Source: ATV News